This contributes to Rust programs generally having good performance characteristics without spending time on optimizations.
That being said of course in almost all of these case you can restructure your program so you don't need to box the values but if it's not performance critical why bother? Repeat a couple dozen times across a large codebase and you have the same pointer chasing issues.
Some patterns of writing code will be really awkward to realize, but there are usually "more rusty" solutions that you start to apply without event noticing. Once you write code with the desired ownership semantics in mind, it's often (relatively) frictionless.
Could you clarify this? It seems like the opposite to me. Borrowing requires lifetimes in type signatures, but boxing yields owned objects, which can be passed around easily like value types.
You won't see these aspects of poor design on a sampling profiler. You will see it by running e.g. perf on Linux and seeing pitifully low IPC and cache miss numbers.